The present invention relates to a machine tool collet, and more particularly to a machine tool collet having an axial stop defined therein for absorbing axial forces.
Machine tool collets for gripping any manner of tools are well known in the art. For example, U.S. Pat. No. 2,346,706 to Stoner describes a conventional collet of the type having a plurality of flat sided gripping members held in a relative position equally spaced about a common axis by means of resilient material disposed between the blades. This material is typically rubber or rubber composition. An example of this type of collet is the well known Rubber-Flex.RTM. collet manufactured and sold by Jacobs.RTM. Chuck Manufacturing Company.
Another type of collet is the well known split-steel collet, such as the collets manufactured and sold by Kennametal.RTM. of Latrobe, Pa.
With the conventional Rubber-Flex.RTM. and split-steel collets for gripping and holding circular tool shanks, the inner diameter gripping surfaces of the respective gripping segments (split-steel collet) and jaw blades (Rubber-Flex.RTM. collet) hold the respective tool shanks and absorb both axial and rotational stresses imparted to the tool shank essentially along the entire longitudinal length of the gripping surfaces. For example, with such conventional collets, the only thing preventing undesired axial movement of the tool shank within the collet is the gripping strength or frictional forces between the jaw blades or segments and the tool shank. Thus, the blades or segments are subjected to sheer forces or stress in both the rotational and axial directions. Prevention of undesired axial movement of the tool within the collet is a critical factor and often is the dictating factor for the required gripping strength between the collet and the tool shank.
Thus, a collet which absorbs axial forces or stresses imparted to the gripping jaws or segments such that only rotational stresses are of concern between the gripping surfaces of the segments or blades would be a welcome and needed advancement in the art.